Rocky Kolb, University of Chicago

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LCDM Beyond the Standard Model
Rocky Kolb, University of Chicago Venice
March 2007
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Precision cosmology
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Radiation 0.005
Chemical Elements (other than H He) 0.025
Neutrinos 0.47
Stars 0.5
LCDM
Free H He 4
Cold Dark Matter 25
Dark Energy (L) 70
inflationary perturbations baryo/lepto genesis
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LCDM reality or substitute for it?
The construction of a model consists of
snatching from the enormous and complex mass of
facts called reality a few simple, easily managed
key points which, when put together in some
cunning way, becomes for certain purposes a
substitute for reality itself. Evsey
Domar Essays on the Theory of Economic Growth
It hardly matters to me whether he Copernicus
claims that Earth moves or that it is immobile,
so long as we get an absolutely exact knowledge
of the movements of the stars and the periods of
their movements, so long as both are reduced to
altogether exact calculation.
Gemma Frisius 16th century Dutch
astronomer
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Standard cosmological model

• Radiation
• Bright baryons
• Neutrinos
• Dark baryons
• Baryo/leptogenesis
• Inflation
• Dark matter
• Dark energy

• Hypotheses?
• Saving the appearances?
• Epicycles?

Do we want one? The goal is not a standard
one, but the correct one!
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Radiation 0.005
Chemical Elements (other than H He) 0.025
Neutrinos 0.47
Stars 0.5
Its OK in practice, but How does it work in
theory?
LCDM
Free H He 4
Cold Dark Matter 25
Dark Energy (L) 70
inflationary perturbations baryo/lepto genesis
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Epicycle I Dark Energy
What is the nature of dark energy
In questions like this, truth is only to be had
by laying together many variations of error.
--
Virginia Woolf A Room of Ones Own
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High-z SNe are fainter than expected in the
Einstein-deSitter model
LCDM
Einstein-de Sitter spatially flat matter-dominat
ed model (maximum theoretical bliss)
Astier et al. (2006) SNLS
confusing astronomical notation related to
supernova brightness
supernova redshift z
The case for L 1) Hubble diagram
3) age of the universe 4) structure formation
2) subtraction
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Subtraction
Wi ? ri?rC rC ? 3H02?
8pG
cmb
WTOTAL 1 (CMB) WM 0.3
1 - 0.3 0.7 WTOTAL - WM WL
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How do we know there is dark energy?

• Assume model cosmology
• Einstein equation symmetry ? Friedmann
  equation H(z)
• Energy (and pressure) content matter,
  radiation, Lambda ?
• Input or integrate over cosmological parameters
  H0, WB, etc.
• Calculate H(z)
• Calculate observables dL(z) , dA( z ),
• Compare to observations
• Model cosmology fits with L, but not without
• All evidence for dark energy is indirect
  observed expansion
• history is not as calculated from the
  Einstein-de Sitter model
• (homogeneous, matter-dominated, spatially flat
  model w/o L)

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Evolution of H (in z or t) is a key quantity
Many observables based on H(z)

• Luminosity distance Flux
  (Luminosity / 4? dL2)

• Angular diameter distance a Physical size /
  dA

• Volume (number counts) N / V -1(z)

• Age of the universe

• Distances

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Take sides!

• Cant hide from the data LCDM too good to
  ignore
• SNIa
• Subtraction 1.0 - 0.3 0.7
• Age
• Large-scale structure
• Dark energy, rL (modify right-hand side of
  Einstein equations)
• Constant (just Einsteins cosmological
  constant L)
• Not constant (dynamics driven by scalar field M
  10-33 eV)
• Gravity (modify left-hand side of Einstein
  equations)
• Beyond Einstein (non-GR branes, etc.)
• (Just) Einstein (GR back reaction of
  inhomogeneities)

H(z) not given by Einsteinde Sitter
G00 ? 8? G T00(matter)
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Tools for the right-hand side
scalar fields (quintessence)
anthropic principle (the landscape)
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Modifying the left-hand side

• Braneworld modifies Friedmann equation
• Gravitational force law modified at large
  distance
• Tired gravitons
• Gravity repulsive at distance R ? Gpc
• n 1 KK graviton mode very light, m ? (Gpc)-1
• Einstein Hilbert got it wrong
• Backreaction of inhomogeneities

Binetruy, Deffayet, Langlois
Deffayet, Dvali Gabadadze
Five-dimensional at cosmic distances
Gregory, Rubakov Sibiryakov Dvali, Gabadadze
Porrati
Gravitons metastable - leak into bulk
Csaki, Erlich, Hollowood Terning
Kogan, Mouslopoulos, Papazoglou, Ross Santiago
Carroll, Duvvuri, Turner, Trodden
Räsänen Kolb, Matarrese, Notari
Riotto Notari Kolb, Matarrese Riotto
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Acceleration from inhomogeneities

• Most conservative approach nothing new
• no new fields (like 10-33 eV mass scalars)
• no extra long-range forces
• no modification of general relativity
• no modification of gravity at large distances
• no Lorentz violation
• no extra dimensions, bulks, branes, etc.
• no anthropic/landscape/faith-based reasoning
• Magnitude? calculable from observables related
  to ?? /?
• Why now? acceleration triggered by era of
  non-linear structure

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Acceleration from inhomogeneities
Homogeneous model
Inhomogeneous model
We think not!
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Epicycle II Dark matter
What is dark matter?
In questions like this, truth is only to be had
by laying together many variations of error.
-- Virginia Woolf A Room
of Ones Own
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WM 0.04
cmb
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WB 0.04
QSO 1937-1009
Ly-a
Tytler
Burles et al.
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Dark Matter?

• Modified Newtonian dynamics (MOND)

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MOND Takes a Bullet
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Dark Matter?

• Modified Newtonian dynamics (MOND)

• Planets

• Size challenged stars

• Dwarf stars

brown red white

• Black holes

• Beyond the standard model (WIMP)

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Dark Matter?

• neutrinos
  (hot dark matter)

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WMAP LSS
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Dark Matter?

• neutrinos
  (hot dark matter)

• sterile neutrinos, gravitinos (warm dark
  matter)

• LKP (lightest Kaluza-Klein particle)

• axions, axion clusters

• solitons (Q-balls B-balls Odd-balls,
  Screw-balls.)

• supermassive wimpzillas

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Disturbing the Vacuum
Particle creation in an external electric field
Particle creation if energy gained in
acceleration over a Compton wavelength exceeds
the particles rest-mass
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Expanding Universe Particle Creation
Arnowit, Birrell, Bunch, Davies, Deser, Ford,
Fulling, Grib, Hu, Kofman, Lukash, Mostepanenko,
Page, Parker, Starobinski, Unruh, Vilenkin, Wald,
Zeldovich, first application (Guth
Pi Starobinski Bardeen, Steinhardt, Turner
Hawking Rubakov Fabbi Pollack Allen)
Its not a bug, its a feature!

• new application dark matter
• (Chung, Kolb, Riotto Kuzmin Tkachev)
• require (super)massive particle X
• stable (or at least long lived)

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Wimpzilla Characteristics

• supermassive 109 - 1019 GeV ( 1012 GeV ?)
• abundance may depend only on mass
• abundance may be independent of interactions
• sterile?
• electrically charged?
• strong interactions?
• weak interactions?
• unstable (lifetime gt age of the universe)?
• UHE cosmic rays?

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WIMPZILLA
or
WIMP
SIZE DOES MATTER
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The nature of dark matter is a complex natural
phenomenon. The neutralino is a simple, elegant,
compelling explanation.
For every complex natural phenomenon there is a
simple, elegant, compelling, wrong
explanation. - Tommy Gold
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LCDM Beyond the Standard Model (OR NOT!)
Rocky Kolb, University of Chicago Venice
March 2007